Safety control mechanism for fuel atomizers



Aug. 14. 1928.

L. l. ALDRICH SAFETY CONTROL MECHANISM FOR FUEL ATOMIZERS Filed July 5,1924 2 Sheets$heet L. l. ALDRICH SAFETY CONTROL MECHANISM FOR FUELATOMIZERS Filed July 5, 1924 2 Sheets-Sheet 2 Patented Aug. 14, 1928.

UNITED STATES 1,680,929 PATENT OFFICE.

LOYD I. ALDRICH, OF PEORIA, ILLINOIS, ASSIGNOR TO PREFERRED OIL BUBNERS,INC., OF PEORIA, ILLINOIS, A CORPORATION OF ILLINOIS.

SAFETY CONTROL MECHANISM FOR FUEL ATOMIZEBS.

Application filed July 5,

My invention relates to liquid fuel atomizing devices and moreparticularly to a safety control means therefor.

The object of my invention is in the provision of a thermal safetycontrol mechanism operating upon an initial failure of ignition of theatomizing device to prevent the flow of fuel to the combustion chamber.

Another object of my invention is in the provision of a thermal safetymechanism included in the secondary circuit and adapted upon a failureof ignition to cut off the fuel supply to the combustion chamber.

Still another object of my invention is in the provision of a thermalsafety member included in the electrical circuit of the fuel atomizingdevice and controlled by the action of the stack thermostat whereby afailure of operation of said thermostat will control the operation ofthe safety member to cut off the fuel supply to the combustion chamber.

Referring to the drawings I have shown in Fig. 1, a diagrammatic view ofa conventional fuel atomizing device and my particular controlmechanism.

Fig. 2 is a side elevation of the thermal safety member, and

Fig. 3 is aview taken on the line 3-3 of Fig. 2.

Referring to the drawings, I have dlsclosed a conventional fuelatomizing device at X, said device to be propelled by an electricalmotor Y, this being the conventional power mechanism for the so calleddomestic fuel burner. Inasmuch as the present application is directednot to a fuel atomizing device but to a control mechanism, therefor, Ihave not thought it necessary to go into a detailed description of thefuel atomizing device, other than to say that a fuel pump 10 and an airpump 11 provide means for mechanically atomizing the fuel and furnishingthe required fuel mixture at the discharge point 12. A blower 13provides added draft through the tube 14 andemission of same through thedischarge nozzle 12.

The above description has been given merely to afford a completeunderstanding of my particular control system in its relation to a fuelatomizing device and it may be understood that any type of well knowndomestic fuel burner might well be used.-

1924. Serial No. 724,542.

Applicant is aware of the fact that systems of control for domestic oilburnersare well known in the art and the present application is directedmainly to a specific thermal safety device for .preventing the flow offuel to a combustion chamber upon initial or subsequent failure ofignition.

At 15 is shown a conventional thermostat adapted to be located in anyportion of a dwelling that is desired to be heated, said thermostatcontrolling the operation of the atomizing device X or rather theelectric motor Y propelling the same.

As is customary in such deyices a relay switch 16 is located between thehouse thermostat and the fuel atomizer, said relay switch in thisinstance being shown as a mercury tube relay, portions making up samebeing as follows:

A bracket 17 suitably supported has connected thereto opposed magneticcoils l8 and 19, said coils being referred to commonly as on coils andoff coils respectively. An armature plate 20 has an edge resting inV-bearings of the bracket 17 so as to oscillate between the coils 18 and19, and carries mercury contact tubes 21 and 22 at the opposite endsrespectively thereof which by the oscillation of the armature plate 20are tilted so that the mercury therein is shifted to make and break thecircuits through said tubes.

' The above relay switch has its magnetic coils in the secondary circuitof the trans former 23, the magnetic coils being energized in saidcircuit to move the contact lever 20 in either direction, this directionbeing controlled by the formal thermostat 15 located in the dwelling,and at a distance,

therefrom. In the normal operation of the device a lowering of the housetemperature throws the house thermostat to an on position, therebymagnetizing the on coils 18,

and attractingthe contact member 20, and

tipping the mercury bulb 21 to a position to energize the electric motorY through the 110 volt circuit from the street.

Obviously the heating of the dwelling to such a degree as to throw thethermostat to the off position would result in the magnetizing of theoff coils and hence the cutting out of the fuel burner.

My invention relates to a safety mechanism controlling the operation ofthe device in case of. an exceptional circumstance namely when therewould be a failure of ignition of the discharged fuel and a conse-'quent accumulation of unignited dangerous fuel.

I accomplish the above result by inserting a thermal safety controlmember in the secondary circuit but adapted to control a switch in the110 volt circuit as well.

My safety control mechanism is also associated with my ignitionmechanism which operates as follows:

A formal gas inlet is shown at 24 and a pipe 25 leads to a pointadjacent the dis charge nozzle of the burner. A valve 26 is locatedtherein, said valve having its stem 2? controlled by a magnetic coil 28,said coil being located in the secondary circuit or rather the circuitfrom the transformer. Similarly a spark coil is shown at 29, said sparkcoil controlling the operation of formal electrodes 30 disposed alsoadjacent the discharge end of the gas tube and the fuel dischargenozzle. The spark and gas are energized inasmuch as they are in thesecondary circuit by the movement of the house thermostat or rather therelay and operate simultaneously with the fuel atomizing device, undernormal conditions igniting the discharged fuel mixture therefrom. Aformal thermostat 31 made up of two metals having a differentco-efficient of expansion is located in any position to be controlled bythe temperatures in the combustion chamber, said thermostat usuallybeing located in the stack. The operation of the stack thermostat makesor brakes an electrical contact by movement of a mercury bulb 32disposed in operable position with relation to the thermal elementstherein.

As said before, the spark and gas mechanisms are energized by themovement of the thermostat and normally ignite the discharge fuelmixture, however, some means must be thrown into operation to controlthe time of operation of these ignition mechanisms and this time elementis the formal thermostat above described. In other words, if there is anignition of the fuel mixture, there will be consequently a raising ofthe temperature in the combustion chamber and hence a movement of thestack thermostat. Under the above described condition, such movement ofthe thermostat will break the electrical circuit of the spark and gasvalves thereby cutting out the spark mechanism and permitting a closingmovement of the gas valve by de-energizing the magnet 28.

My thermal safety mechanism is intimately associated with this ignitionmechanism and is made up of the following portions. A thermal orbi-metallic strip 33 is suitably supported at 34 in a longitudinalposition. A resistance coil 35 surrounds said member, said coil being inthe secondary circuit and connected by the wire 36 to the transformer.The connection of this resistance coil 35 to the transformer is such,due to the ground 37, that an electrical circuit will also be maintainedtherein either during the operation or non-operation of the fuelalomizing device, with the result that normally a considerable heat willbe developed in said resistance coil and hence a corresponding movementof the thermal member which it surrounds. The secondary circuit normallyinduces such heat through this coil 35 as to move the thermal member 33to a downward position and upon a lessening of the current to suchresistance coil, there would be naturally a decrease of heat and aconsequent rise of said thermal member. The projecting or operating end38 of this thermal member has operative engagement with a switch membershown in detail in Figs. 2 and This safety switch member is suitablysupported by means of brackets 39, and is made up of the followingportions. Au insulated block 40 is pivoted in the brackets 39 and has amanually operable lever 41 connected thereto. A pair of separatecontacts 42 are supported by brackets 43, there being a separate contactpoint 44 upon the insulated block 40 for each contact 42. A downwardlyprojecting portion 45 on the insulated block has a protruding lug 46thereon, said lug projecting through an aperture 47 in one of thebrackets 39. This lug is adapted to engage a catch portion 49 upon alever 50 pivoted at 51 on the above mentioned bracket 39. Now this lever50 is controlled by the movement of the thermal member 33 inasmuch asthe projecting end 38 thereof underlies-one end of said lever as shownin Fig. 3.

Obviously when the thermal member is suitably heated and depressedthereby, the end 52 of the lever resting thereon will drop down to aposition wherein the latched portion 49 will engage the pin 46. Thissafety latching movement is accomplished by manual movement of the lever41.

When the current to the coil 35 is diminished there is a decrease oftemperature which serves to straighten out the thermostatic element 33and raise the outer or free end thereof, thus elevating the end 52 ofthe lever 50 and releasing the latch 49 from engagement with the pin 46.Upon release of this latch the insulating block 40 drops by gravity andbreaks the connection between the contacts 42 and 44.

One pair of contacts 42-44 controls the circuit to the motor Y of thefuel atomizing device while the other pair of contacts 42-44 are in thesecondary circuit from the {aransformer that operates the magnetic re-The operative relation of m described thermal member in the secon arycircuit may perhaps be more clearly understood if it be said thatnormally the circuit controlling said thermal member will heat themember 3 to such an extent that it will maintain a depressed position.However, upon the use of current in the secondary circuit to energizethe spark coil as well as the gas coil the capacity of the transformerwill be strained with the result that a less amount of current can atthis time be used by the resistance coil 35 and hence a decrease in theheating thereof occurs.

I may connect the operation of my described thermal safety member withthe operation of the ignition mechanism of the fuel burning device now,by saying that said thermal member is maintained in a lowermost positionpractically at all times due to the constant heat maintained by thecurrent passing through the coil 35. The thermal safety switch is atthis time latched so as to hold the contacts 42 and 44 in a closedposition. Now upon the energizing of the fuel burning device dueto themovement of the thermostat, and consequently the relay, With asimultaneous energizing of the spark and gas coil, due to the movementof the relay, a decrease in the temperature of the coil 35 will takeplace at the same time as above described, due to the straining of thecapacity of the transformer. An immediate movement of the thermal member33 will not take place but a very gradual movement will however begin.As above described, if there is a normal movement of the stackthermostat due to a rise in temperature in the combustion chamber therewill be a consequent cutting out of the spark and gas coils. Thiscutting out of said coils will naturally permit the full capacity of thetransformer being directed to the coil 35 with a resultant rise intemperature and the movement of the thermal member again to its first ornormal position.

Of course, it is understood that the movement of the thermal member istimed to such an extent that no tripping of the safety switch ispossible until such thermal member has reached a considerably elevatedposition.

In case of failure of initial ignition there will be no movementtranslated to the stack thermostat and hence the snark and gas coilswill use a considerable portion of the transformer capacity with theresult that eventually the decrease in heating of the coil 35 cessationof com" ustion condition after initial ignition, there will be a secondenergizing of the spark and gas coils and if the discharging fuel is notignited at this time, the safety device will OJerateas above describedto cut out the uel atomizer.

What I claim is:

In an apparatus of the class described, the combination of a burner,motor operated means for supplying a fuel mixture to the burner, athermostat for controlling the operation of the motor operated means, a

transformer having a coil in the secondary circuit for heating saidthermostat, and a burner igniting circuit shunted around said heatingcoil so that closing of the latter circuit diminishes the current in theheating coil of the thermostat and permits a slow motor stoppingmovement of said thermostat.

In testimony whereof I afiix my signature.

LOYD I. ALDRICH.

